Mine-drill



1; K-ATUL KA.

MINE DRILL.

APPLICATION FILED FEB. 12.1920.

Patented Dec. 7, 1920.

2 SHEETS-SHEET l- 11. KATUL'KAr .MINE DRILL.

APPLICATION FILED FEB. 1.2, 1920 Patented Dec. 7, 1920.

UNITED STATES PATENT OFFICE.-

J'OHN KATULKA, 0F NANTICOKE, PENNSYLVANIA.

mmn-nmil.

Specification of Letters Patent.

Patented Dec. 7, 1926).

Application filed February 12. 1920. Serial No. 358,118.

. and use the same. i

This, invention relates to improvements in coal drills or angers and has for its objects to provide a drill which will be more durable and effective in operating than the devices heretofore commonly employed.

\Vith this and other objects in view the invention consists in the construction, the combination, the detail, and arrangement of parts as hereinafter more fully described and claimed.

In the drawings:

Figure 1 is a side elevation of a three cutter bit embodying my invention.

Fig. 2 is a view at right angles to Fig. ,1.

Fig- 3 is a bottom view of Fi 2.

Fig. 4 is a modified form wlth four outters in a position similar to Fig. 1.

Fig. 5 is the same modified form in the same position as Fig. 2;

Fig. 6 is the same modified form in the same position as Fig. 3.

In the embodiment of my invention I provide a bit having a polygonal shank 2 provided with a recess 3 for retaining the said bit in a stock, the said bit extending into prongs or cutters 4, 5, 6 and 7. -These prongs are all integrally formed with the said shank, there being a recess 8 between prong 5 and prong 6 and a wider recess 9 between prongs 4 and 7. There is also a short recess 10 between prong 6 and prong 7.

Prongs 6 and 7 extends substantially in longitudinal alinement. with the said shank 2 and are webbed between each other at 1 1 the said web tapering from the said shank where it is substantially the thickness of the said shank down to the recess 10, and there is provided a rib 12, so that the two prongs 6 and 7 are each substantially triangular in cross section with one side of said triangle everlapping a like side of said triangle 011 the other said prongs. In the boring of coal there is muclr stress upon the prongs 6' and 7 and frequent difliculty has been had owing to the breakage of the central bits. By this improved structure the breakage is reduced to a minimum and the bit improved in efficiency.-

hat I claim is:

1. A bit comprising a single piece of metal of polygon shape to form a shank bits extending therefrom, said bits being oi substantially triangular cross section with their cutting edges in the plane with one side of the triangle, the opposed back an le being a continuation of an edge of t e polygonal shank.

2. A bit comprising a single piece of metal of polygon shape at one end tov form a shank, op osed edges of said polygon egrtending to f brm the backs of a pair of bi s, and an integrally formed auxiliary cutter.

*3. A plurality of integrally formed bits of triangular cross section extendin in one direction into a polygon shank an in the other direction into cutters, the cutting edges of said cutters substantially parallel with the' sides of said shank and the edges of said polygonal shank extending to back said cutters and give rigidity thereto.

In testimony whereof Iafiix my signature.

JOHN KATULKA. 

